When an obstacle appears suddenly in front of a vehicle, it is necessary to prevent the vehicle from colliding with the obstacle by operating the brake and decelerating the vehicle. However, when the driver does not recognize the obstacle inadvertently, the vehicle may collide with the obstacle.
An adaptive cruise control (ACC) which may also be referred to as a smart cruise control is a function to prevent collision with a preceding vehicle ahead. The ACC system detects a forward vehicle and adjusts a speed of a subject vehicle equipped with the ACC system according to a distance between the forward vehicle and the subject vehicle. Specifically, the forward vehicle is detected through a sensor mounted on the front of the subject vehicle, a distance to the detected forward vehicle is measured, and a collision with the forward vehicle is prevented by adjusting the speed of the subject vehicle.
In a typical ACC apparatus mounted on the subject vehicle, an object located in the forward direction of the subject vehicle among objects detected within a certain forward range through a radar in front of the vehicle is assumed to be the forward vehicle, a distance between the subject vehicle and the forward vehicle is calculated, and only the speed of the subject vehicle is controlled based on the calculated distance.
However, since such the conventional ACC apparatus may fail to detect a forward vehicle present in the front lane in a steep curve state, or may recognize a vehicle travelling in a side lane as a forward vehicle, there is a problem that it is difficult to track a forward vehicle properly.